The objective of this work is two-fold: first, to examine the hypothesis that there is a relationship between the etiology of skin cancer and the levels of certain trace elements in blood or hair. The elements of interest include selenium, arsenic, cadmium, zinc, copper, and lead. The issue relating to selenium is of the greatest interest. Second, the hypothesis that occupational exposure to herbicides, pesticides, or fungicides, including those containing arsenic as well as other groups of aromatic or aliphatic hydrocarbons, is a significant risk factor for the development of skin cancer. A case-control design in which subjects from a specific dermatologic clinic practice in the eastern part of North Carolina is anticipated. Four groups of skin cancer patients of different types will be compared with a group of dermatologic controls (persons with skin disease other than, and unrelated to, skin cancer). The disease outcome of interest is skin cancer, and the risk factors of interest are selenium level, other trace element levels, and occupational exposure.